FQDN stands for Fully Qualified Domain Name.
It refers to a complete domain name consisting of a host and a domain name.
The domain name itself has comprised of two parts: the second-level domain and the top-level domain.
So, for the example of www.exampledomain.com, 'www' is the host, 'exampledomain' is the second-level domain and '.com' is the top-level domain